The initial D&D campaign surfaced out of a Castles and Crusades Campaign. The original alignments were based off of Three Hearts and Three Lions with Law = Civilized and Chaos = Feral. Neutral was the borderlands between those two realms.
The next fantasy campaign was Barker's with Good/Evil for alignments, but the Good was stasis and the "Evil" was change.
At the same time, there was Moorcock's Law and Chaos with Law = Good and Chaos = Evil (and the chaos gods were worshiped with cries of "blood and souls" and similar things). Of course Moorcock did not stay still, and his Law/Chaos eventually moved to Stasis/Change. Moorcock's Neutral was exemplified by Tanelorn -- where people attempted to step aside from the wars of the gods.
My preference was Order / Chance (Tychism). Though my law/chaos eventually shifted to Order (external rules) vs. Anarchy (internal whims).
In each of these the possibility of a good/evil axis also fits in. Good can be defined a number of ways, but the two that fit fantasy campaigns are (1) seeking positive outcomes for the greatest number and (2) aligned with the positive energy planes -- both resisting entropy.
Evil is either (1) rapacious self serving action or (2) malicious action. Both are aligned with the negative energy planes (or why all undead that energy drain end up evil) -- and increasing entropy.
For the most part, #1 is the general understanding of evil -- something that admittedly creates some tension with players who want to play #1 as neutral and assert that as long as their rapaciousness isn't malicious, it isn't evil.