Sneering that evolution is "just a theory" - as though scientific theory is mere speculation that someone is pulling out of their ass (like, say, RELIGION) - shows you up to be an ignorant buffoon. Either learn what the term really means or stop using it.
If the theory of evolution is true and man evolved from monkeys and/or apes why are there monkeys / apes still around? Well if you spend a little time to READ & understand the theory of evolution and the underlying concepts you will hit upon the answer outlined here.
A very wide range of sources provide the supporting evidence for Evolution e.g. Fossil record Embryology Molecular biology Presence of Vestigial organs Biogeography Sequence similarity between species that are also observed as a time dependent change in junk DNA Transitional fossils predicted in 1859 by Darwin provide rich evidence e.g. Tiktaalik (transition between fish and amphibians) Ichthyostega (transition between amphibians and reptiles)
What it's Science is not : It is not based on some old holy book, blind faith, wishful thinking, religious dogma & belief systems, delusions or something somebody preaches (& believes in) without any solid factual evidence & proof via experiments