Need to deal with g4xf3, and Nc4 anyway so that reduces options a bit.

How has theory on the english attack and anti-english developed since 2015? What about the 6. f3 lines?

Najdorf English Attack, when will the final verdict be reached?

If the English attack is not so good anymore, how can white come out of the opening with an advantage in the sicilian najdorf? If he cannot, why doesn't everyone play d4, c4, or the Moscow variation of the sicilian instead?

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be3 Ng4 7. Bc1 Nf6 8. Be3 Ng4 9. Bc1 is best

cool

it is a good opening

I suppose that if there is no white advantage to any first move, GMs must simply not be so familiar with 1. b3, seeing as they do not play it nearly as often as 1. e4 or 1. d4? Or what about the alternative explanation, that 1. e4 provides a greater chance at advantage than 1. b3?

 1) Show to us where is White's advantage in the English Attack vs Najdorf defense both in e5 and e6 approach by black ....because i haven't found any.

2) The opening advantage is something most of the times spatial. It can be translated as: " slight initiative " , " space advantage " , " more active pieces " , " potential passed pawn ", "better-attacking chances " ,  " control of the center ". e.t.c

Unfortunately or fortunately chess is more complex than all this and as the game continues beyond the opening stage you realize that is quite difficult to keep hold this " advantages " forever without allowing the second player the merit of his/her play that's why most of the players concluded that there is no advantage in any White's first move either white's decides to occupy the center from the beginning or delay...

That is the practical approach of the game played by humans. If you are interested only for Artificial Intelligence chess ask Leela. I don't think this thread can give you more answers.