I know what moral relativism is, as I stated above:

Putting up a philosophical argument about moral relativism just degrades the discussion into nothing, because your line of reasoning is this: if you don't
know everything, then you can't talk about anything!

This makes any argument about anything invalid, and you might as well kill every social program that promote anything, because it's all relative.

Again, you are confusing absolute and unchanging with what can be evaluated scientifically. Just because something changes over time or in different contexts, it doesn't you can't talk about it in scientific terms.

Morals are contingent upon the culture of your time (your zeitgeist). That being said, you can act accordingly, with a scientific approach. What other approach would you use instead?

In any case, we have fundamental needs that need to be satisfied, and that isn't based on somebody's opinion. We can start from there and build up the rest, bit by bit.