i can beat elo:1100 computer but i can't beat elo:700 players
You're beginning to learn.
Because engine is a poor substitute for playing weaker humans. Engine rated 1100 will just be programed to drop pieces randomly, humans will not do it exactly like this (even though 700 rated will drop pieces there will probably be some reason behind it). 1 100 engine will just left its queen hanging completely at random.
A boy will play like its level and then randomly drop a piece. Real people don’t really do that. I mean they do hang pieces, but usually not in such a completely obvious way, and if they do, then there’s usually a reason for it. The computer will just give you a knight or something for no reason because the computer decided that this move it “has to play badly” so it can accurately represent how it thinks its rating should play.
good luck...
The strongest engines can beat any human including super GMs, but it is tough to build believable human like lower level engine. 
I haven't played the computer for a while but when I did I found their play wasnt consistent. For example they would play the openings well but then make nonsensical blunders in the middle game. Often not by hanging pieces but by ignoring strong recaptures. To beat the computer I could just make a daft sacrifice and win the material. This was on 1200 rating. It was more like a 1400 opening and 600 middlegame (apologise to 600 players). People aren't like this (most of the time).
try maia 1 (1100 elo) bot. it is the nearest humanoid player.
it is available on lichess. and there is a website for the project
