You can do squats, rows, chest press & overhead press with dumbbells, though they're a little different technique & you won't be able to go up in weight in such small increments - still not bad though. Dead lift you'll struggle though as you need a proper bar for that.
My gym is the same (rubbish); no power racks, only one squat rack (and that's not a proper one), not many bars etc...
You can do squats, rows, chest press & overhead press with dumbbells, though they're a little different technique & you won't be able to go up in weight in such small increments - still not bad though. Dead lift you'll struggle though as you need a proper bar for that.
My gym is the same (rubbish); no power racks, only one squat rack (and that's not a proper one), not many bars etc...