All canon EF or EF-S lenses will work on the 500D camera body. Canon FD lenses, lenses manufactured before canon switched to the EF system require an adapter to convert to the EF system, the adapters are mainly 3rd party offerings , but there are issues.
Older 3rd party lenses (sigma) designed before digital will not work on the digital bodies (my 2 sigma lenses that worked on my Canon 500N 35mm film camera, wouldn't work when I bought my 20D), unless they were rechipped (wasn't worth it).
It sounds like the guy you bought the body off was using older lenses that were probably not chipped to work with a digital body.