Current gods are Humanity's gods. They were almost all created by humanity, after all, and it would be rather odd to believe that in the millions of years of the Eldar's existence, there were no wars or massacres large enough to trigger Khorne existing, while the Mongols managed to set him off, unless the psychic energy of the Eldar was feeding something else, which happened to be on less genocidal/parasitic terms with their followers.
The Chaos Gods are not humanity's gods - they're gods created by everyone in the galaxy. The whole "they were formed because of humanity" was retconned a long time ago because it was stupid and didn't make sense. I urge you to stop preaching such falsehoods before someone ignorant of the truth begins to believe you. This is the truth:
Khorne, Tzeentch, and Nurgle developed over millions of years due to the War in Heaven, gaining sentience around the time of humanity's middle ages. The two things aren't related - it's pure coincidence.
Humans, while they make good food for Chaos and have a decent Warp signature, had very small numbers back in those days and were little more than a larger-than-average drop in the ocean in regards to what created the Chaos Gods. It was the quintillions of other life forms in the galaxy that contributed almost everything to the creation of those three Chaos Gods.
Hell, even in the tens of thousands of years after they'd gained sentience, even after humanity's numbers increased to the quadrillions, the Chaos Gods were still barely active, doing nothing of note.
I know very little about Ynnead (Eldar death) and Malal (Human destruction). The latter being completely ignored, the earlier being obscure I think.
You're right to know nothing about Ynnead, because she doesn't exist yet. The Eldar, as of current canon, are still working on getting enough soul stones to birth her.
As for Malal, he is not the Chaos God of Human Destruction because:
a) He doesn't exist, and
b) If he
did exist, he would be the Chaos God of Anarchy and Chaos, the representation and manifestation of Chaos' self-defeating nature.
Ive always found the whole -mongol invasion -> khorne- bit stupid and thought it was a relic of the 80s.
You have the right idea.
I quite don't like how several of the chaos gods are too tied to mankind.
They aren't. If every single human in the galaxy were to cease to exist in the same manner as Horus, the Chaos Gods would still continue to exist and would merely be badly weakened. You can kill literally everything in the Materium and they would continue to exist, because while they would be
far weaker than they are now, they are sustained by ALL emotions, including the emotions generated in and by the Warp.