Just get your head around a few basic facts. Life first arose on earth some 3 billion years ago. ALL forms of life present today derive ultimately from the very first life form. ALL life forms therefore are equally old and all have always existed in some form or another. That some form or another is important.
Of course the ancestors of humans were contemporary with the dinosaurs. Yes, they were alive some 65 million years ago, BUT you wouldn't recognize them as human. Our ancestors back then were little furry creatures with tails, about the size of a rat. Close inspection might have revealed that even back then they had some human like features. They probably had forward directed eyes to give them binocular vision. They could possIbly see in colour. They would have had 5 digits on each limb as we do. They probably had approximately the same number of teeth as we do. They most definitely had warm blood, nipples and fed their young on milk. They possibly had nails rather than claws.
Now, great big creatures with enormous bones like dinosaurs, whales and mammoths, fossilize well, but creatures with small fragile skeletons like hummingbirds, bats, mice, shrews and the ancient shrew like ancestors of humans would be fantastically lucky to be fossilized at all. Their little carcasses would be eaten by predators or scavengers, by ants, maggots and beetles. Only a fool would hope ever to find a fossil of one of our direct ancestors from the time of the dinosaurs, but that doesn't mean they didn't exist. We know they existed because we exist today. Remember, all forms of life present today, have always existed at every time in the past, but not necessarily in a shape we would instantly recognize as ancestral to their present form