Humans have some 10's of new mutations
each and those are the ones that have had the really bad ones weeded out by spontaneous abortion (something like half of all fertilizations).
These are, at worst, not too bad and clearly most are neutral.
That means that there are between 50 and 500 billion mutations in humans every generation. Since we know that some are beneficial it only takes a very, very small proportion to produce lots of beneficial mutations (e.g, posters here who never develop wisdom teeth).
At 1/10 of 1 % we get between 50 and 500 million beneficial mutations a generation or a rate of 2 to 20 million a year. Is that enough for you?