The Hebrew word satan means "accuser" or "adversary". It can be used in a general sense rather than as a proper noun. This does not mean that all occurrences of the word refer to a generic accuser. For example, Luke 10:18,
I saw Satan fall like lightning from heaven,
is clearly referring to a specific individual. But in 1 Kings 11:14,
Then the Lord raised up against Solomon an adversary, Hadad the Edomite, from the royal line of Edom,
the English "adversary" is translating Hebrew "satan". Clearly Hadad is not the actual devil.
In the book of Job, "Satan" appears in heaven and is instructed by God to torment Job. This matches the idea that "satan" can be a job title of an angel, who works for God but whose task is to tempt people and cause suffering. In particular, such a "satan" is not opposed to God. In the Hebrew, it is actually "ha-Satan", "the satan" or "the accuser" (eg in Job 1:6).
Historically, Jewish ideas about Satan changed significantly during and after the Exile, perhaps due to their exposure to Babylonian mythology. The idea that Satan is in active rebellion against God is certainly much more prevalent after this time, whatever the cause. Previously, the dominant view was against an independent adversary, and in favour of God controlling everything, good or bad.