Most scientific evidence in all fields is inferential rather than direct. For example no-one has visited those little lights in the night sky to check that they are suns like our own, yet few seriously doubt that fact, derived from copious inferential evidence. The inferential evidence supporting evolution is at least as abundant. What mechanism do you believe prevents lots of microevolution from adding up to macroevolution? No creationist AFAIK ever suggests how this works.
