"Good" according to the old testatment.

[Godscreated]

8He hath shewed thee, O man, what is good; and what doth the LORD require of thee, but to do justly, and to love mercy, and to walk humbly with thy God? (Micah 6)

1) act justly
2) love mercy
3) be humble towards God

It seems to me, this is saying, this is all that is good. I guess the notion "act justly" can encompass being good in general, because being good is being just. But what if it extends beyond justice. What if you go out of your way to do extra good, and be charitable or volunteer, all that is beyond just being just, but is extra good.

I would say this would make sense deeming all that is necessary to be good. Not all that which is good.

Also something to notice is that this verse seems to be saying that humans can achieve this, as it's "required from their Lord". God would not require something that cannot be achieved.

Now in the new testament, there is a line, that no one is good but God. Now if we take that as literally true, it seems that there is a contradiction here.

Also I would add, is then the "requirement from the Lord" not achievable by non-Christians? It takes 1) acting justly 2) loving mercy 3) being humble towards God.

If this all that is required in the old testament, then obviously, believing in the old testament or bible is not a requirement. That is not required by God, since all that is required by God was those three things.

Looking forward to your feedback.

First, God did give man requirements they could not attain, "the law given to Moses," this law was not given to cause man to sin, it was given to show man how weak he was and how much man needed God.
Second, the three requirements you have given can cover many things, they are let's say categories and within these categories are many requirements.
Third, when scripture says, no one is good but God. It means that no one can be perfectly good as God is.