Why do we have pawns?

Pawns are the soul of chess.

Imagine a war fought without infantry,thats exactly the situation in chess without the pawns.

Maybe it is related to why we have an appendix.

without pawns the pieces are sitting ducks.

  I would say that pawns do a great job of outlining your position. They can stop minor pieces and heavies from advancing down the board into your your camp. Best of all, they can be promoted at the end of the game, making the endgame a very interesting phase of the game. I do see your point that pawns can sometimes get in the way, but I do think that pawn lead to a more interesting game of chess.

What about the Evans Gambit?

cannon fodder.

What kind of war would it be without infantry? Pawns are expendible, and if used properly are the deciding factor in your game. All openings have a pawn in them, all endgames go back to how you used your pawns. Basically, pawns are the soul and blood of chess. 

it is the meat shield so every game isn't mate in 4

Chess is a war game and pawns are foot soldiers (or as batgirl wrote "cannon fodder").

Like in real life, they are usually the first to be sacrificed... :-(((

I agree. Why bother with pawns when we could use queens instead. While we're at it, rooks and bishops are kinda pointless too, essentially just defunct queens. I propose we replace all chess pieces that aren't Queens, Kings and knights with Queens! 

That should simplify chess immensely.

 you  have pawns because we need little people to be.

chess is supposed to be like life (otherwise you've gone full nerd) so the pawns are like kids. what did i win ?