Rather than start with the biblical basis for the doctrine of 'original sin', it might be useful to start with the origin of denial of this very early Christian belief. Here is a quote from a scholarly book, defining its origins:
Pelagianism - school of thought named after Pelagius (354 - 418?) and
promulgated by Julian of Eclanum (c. 368-455). They taught that the
human will was capable of spiritual good without the aid of God's
grace, and that sinless perfection was possible in this life.
Augustine and Jerome were chief critics of Pelagianism, and it was
condemned by church councils in 418 and 431. Pilgrim Theology p.470,
Michael Horton, Zondervan 2011
It wasn't until the mid-4th century that clear opposition within the Church to this long-held Church doctrine became solidly clarified, and it can be seen that the objection was that human free-will could not be incapable of choosing to do good. That is diametrically opposed to claiming that all humanity is tainted with sin and dependent on the grace of God to be delivered from that.
The debate has raged on ever since, as shown in the 1610 'Remonstrance' of those supporting the recently deceased James Arminius and what he taught about free will, or human ability. This came to be the first point of Arminianism: that man, although affected by the Fall, was not totally incapable of choosing spiritual good, and was able to exercise faith in God in order to receive the gospel and thus bring himself into possession of salvation.
In response to that, the Synod of Dort in 1618 responded to that first point with the view that man is totally unable to save himself on account of the Fall in the Garden of Eden being a total fall, not a partial one. If man cannot save himself, then only God can, and it is up to him to decree how he will do that. With the best will in the world, fallen sinners cannot get themselves out of the mire they find themselves in. Please note, however, that the doctrine of original sin does not say that man's total inability is due to some supposed total depravity. Man is not as depraved as he could be. That's not what's being claimed. It is that man's natural state (after the Fall) renders him totally unable to gain, or contribute to, his own salvation.
Now we can deal with what you first asked for: the biblical basis for this doctrine. As it would require pages and pages of text to quote all the scriptures, I will just list some sample sources and ask you to read them all for yourself. This is by no means an exhaustive list, but just one that will begin to open up the biblical basis you seek.
Genesis 6:5; Job 14:4; Job 14:4; Psalm 51:5; Jeremiah 13:23 & 18:9-10 & 14; Mark 4:11ff; Romans 3:9-12 & 23 & 5:6, 8, 10-14 & 7:10-8:2; 1 Corinthians 2:14; Ephesians 2:1-10; Colossians 2:13-15; Titus 3:3-5; 1 John 1:8-10.
