Lord of the memes

I am quite sure he based them on stereotypical views that were prevalent during his times and not actual people. Still he showed that these perceived differences come from their internal worst traits manifesting in their views on others and can be overcome for the good of all.

You are not wrong but nuance in reading is important.

1. Those are some nice claims, got any sources for them?

2. If your claims are true, it would be a quite kind depiction of stereotypical jews for the times. Dwarves were a very hardy and highly skilled people, who were quite generous with their craft. Almost the only bad traits they had were because of the incredibly powerful magic rings Sauron gave them, which were designed corrupt them and make them his slaves. They almost fully resisted that corruption, just becoming greedy and isolationist instead.

3. The story transpires in a world where there are actually good gods that help people and an evil god (Morgoth, and later demigod-ish Sauron) that is trying to corrupt and rule the world. I don't think the decline of Men is a metaphor for growing secularism (Tolkien was famously a BIG hater of metaphor and allegory as story telling devices) as much as it is a direct consequence of their in-universe growing secularism and the same happening earlier in the world.

4. "Eastern/Southern men given to evil on brown people" What do you mean? The Eastern/Southern men are the brown people. The reality of it is that the story is one of war, and we're seeing it told from people on one side of the war. That means we're gonna get mainly negative views on the other side. Even so, the first time we see a Man of Harad in the books, the first thought we're given from one of the characters is Sam thinking this about him:

He was glad that he could not see the dead face. He wondered what the man’s name was and where he came from; and if he was really evil of heart, or what lies or threats had led him on the long march from his home; and if he would not really rather have stayed there in peace.”

This is to me a nod towards the Men of Harad (at least, likely all the easterlings) not actually being evil but only being decieved by Sauron (the Deciever).

In general, Tolkien was born in 1892. He likely wasn't a paragon of equality, but i also don't think he portrays any kind of racism or xenophobia if you look past the very surface level of his writings.