The Carolingian Renaissance produced much reforms, including in the church, as well as much learning, patronized by Emperor Charlemagne and his grandson Charles the Bald. See Ken Graham's answer for more details.
But in the area of Ethics, the area the OP was focusing, the period "did not give rise to innovation in moral thought", according to a 1992 book chapter Early Medieval Ethics by G. Scott Davis, a professor in Religion & Ethics at the University of Richmond, which can be read online or in pdf.
However, Stephen Stewart, writing in a Philosophy Now magazine article "The Carolingians" (2005) has very positive assessment of the period within the larger scope of philosophy:
Thinkers such as Alcuin of York (c.735-804) and John Scottus Eriugena (c810-c877) are not as well known as their later counterparts. However, their substantial role in the history of philosophy should not be ignored or underestimated. Critics may say that they contributed little of originality and merely transmitted the philosophical musings of the ancient Greeks and others.
...
It is doubtful that the likes of Eriugena will ever hold as great a position as Renaissance thinkers such as Macchiavelli either in the popular mind or in the pantheon of western philosophy. However, to ignore them and their contribution is to distort the history of philosophy and the lasting legacy of the Carolingians.
Here are then, the 2 major contributors to early medieval philosophy of lasting significance during this Carolingian Renaissance:
Alcuin of York
c 735-804 AD: Cath. Ency. entry, Wiki. He wrote "De Virtutibus Et Vitiis Liber" (Book about the Virtues and Vices): Latin text (pdf here), English translation.
Quote from "Early Medieval Ethics":
The works of Alcuin (735--804), the leading figure in Charles' reform, reflect
a period of consolidation and are instructive in their concerns. Introducing
his De grammatica, for example, Alcuin pens a short introduction to philosophy which stresses, in Boethian fashion, the need to free the soul from
the vicissitudes of Fortune and transitory involvements and to discipline
itself with study. A dialogue on rhetoric closes with a discussion of the
cardinal virtues and their parts. His treatise On the Virtues and the Vices,
drawn primarily from scripture and the sermons of St. Augustine, presents
a concise statement of the relation of faith and works, emphasizing the
primacy of charity, fear of God, and chastity as the vita angelica. Alcuin
traces the fundamental moral directive to reject evil and do the good back
to Psalm33, and derives from it the four cardinal virtues. It is of interest that
a list of eight principal vices and a new set of subordinate virtues emergea
set which includes peacefulness, mercy, patience and humility.
Quote from "The Carolingians":
... Under Alcuin, knowledge was delineated into the seven liberal arts: the verbal arts of the trivium, namely grammar, logic and rhetoric and the mathematical arts or quadrivium of arithmetic, geometry, music and astronomy. According to David Luscombe, this classification of knowledge served as a cradle in which subsequent philosophical thought was nurtured.
... He also helped establish a thorough grounding in the arts as a prerequisite for the educated classes for centuries. As a result, while ever more fractious theological disputes broke out about the nature of souls, predestination and free will, philosophical concepts would increasingly be put into good use.
... It was also Alcuin who saw to it that the Consolation of Philosophy by Boethius became a central part of the arts curriculum, ensuring a central role for the subject, according to Carabine. She wrote: “...the emphasis on reason in Christian education signalled the beginning of a tradition that was to come to its full blossoming in the works of the thirteenth-century master Thomas Aquinas.”
John Scottus Eriugena
c 800-877 AD: Cath. Ency. entry, Stanf. Ency. Phil. entry, Wiki. His major contribution was in the foundations of ethics in relation to God's foreknowledge and predestination. His archbishop engaged him to refute a growing heresy led by Gottschalk and as a response he wrote De divina praedestinatione (On Divine Predestination). Peter Adamson published a podcast "198. Grace Notes: Eriugena and the Predestination Controversy" on that very topic.
Quote from "Early Medieval Ethics":
Half a century later John Scotus Eriugena (c. 813-880), working at the
court of Charles the Bald (Charles I, King of France, 823-877; r. 843-877),
engaged in a heated dispute on predestination and foreknowledge which
relates directly to the foundations of ethics. If God is omniscient, are not all
human actions immutably fixed and inescapable? Taking his start from
Augustine, Eriugena argued that language about God must of necessity be
metaphorical and nonliteral. Hence talk of God's knowledge as preceding
human acts is misleading. God exists in an eternal present without change.
His understanding remains merely foreknowledge in the divine eternity
and is in no way coercive. Eriugena remained primarily a cosmologist,
however, though book four of his De divisione naturae does outline a moral
psychology based on the allegorical interpretation of Genesis 3.
Quote from "The Carolingians":
... He develops the notion of negative theology which he attributed to pseudo-Dionysius and explores the idea that descriptions of God can only be held to be true when they are negated. God is by his very nature unknowable, even by himself – for if he was to know himself, he would be in a sense circumscribed and limited.
... Eriugena also had the audacity to question the shibbolleths of the great Augustine and shaped Christianity with a bold infusion of Neo-Platonism, uniting eastern and western philosophy. The influence of the “generality of scope and unaccustomed ideas” in his thought has been far-reaching. ...
... Writers have pointed out that Eriugena manages to reconcile the seemingly irreconcilable, laying forth the relation between God and creation in an ingenious way which preserves both divine transcendence and omnipresence. ...