[Sharkû]

I haven't made a quote-by-quote analysis of a post in ages, so please bear with me for once.

If Non-white people alway is described as evil beings, and easy to corrupt...

All men are easy to corrupt, none of them are (inherently) evil.

should Toliens work be considered a myth of Europe

In a way, that was still Tolkien's underlying intention. The events described are a) from the perspective that seemed most natural to the person that was JRRT and, b) that was the most interesting in the course of the Three Ages since it was the North and North-West of ME where the brunt of the action took place.
Euro-centrism? Perhaps, but do not disregard, for example, the fact that all men awoke in the East, and are created equal as far as we know. Men are nobled by their deeds (that goes mainly for the Atani), or the deeds of their ancestors, not their sole lineage.

I am yet to find a Non-white man doing a noble act

Unfinished Tales has Sador, Drúedain in Númenor; Silm. has the people of Bor; LOTR has again the Woses, Breelanders, and of course the Haradrim (if valor in battle isn't a noble deed, what is?).

Non-whites are not born evil, that is a thought that cannot fit in the cosmology at all. The only thing one may inherit at birth are the emnity with another people for historical or political reasons; or an aftermath of the primeval corruption of Man by Morgoth. As is shown in that on what we can glimpse on beyond the events of the Ring War, trade and peaceful coexistance was of course possible -- cf. the repenting of the Dunlanders after the Battle of the Hornburg, the release of the Mannish slaves of Mordor, etc.

The purity of blood seems a more difficult matter. I could at great length explain its mythological importance that would justify the use of it as a topos in a work of fiction, and could only marginally touch its importance in Biblical tradition.

One could also quote and explain from the Legendarium proper: that less noble men mainly implies men that were less long-lived, not necessarily less virtuous; and that the most ardent defenders of the purity of lineage were in fact on the morally wrong side, as can be seen in the Kin-Strife of Gondor.

I could refer to my abovementioned statement that it was only the deeds of the Edain in the War against Morgoth that founded the nobility of their lineage in first place, and that the rest of their nobility was made up by their partially Elven descent through Elros.

All of these may not wholly answer the question one might still ask just why the author chose to write it the way he did. But we do know the Professor certainly was not racist; and as I have hoped to prove to some extent, neither is the work.