What's needed is logic. A pint (468ml) of skimmed milk contains MORE than 20g of protein. An 8oz steak contains more than 20g. A 125g of tuna contains more than 20g. Throughout history we've eaten, even when we were shorter, small and lighter as a race than we are now, consistently more than 20g at a time. Be that in blood, insects or goats milk we can, we have and we will.
The question, for which Steve's reply is a little relevant is 'should we'? It depends. I outweigh Steve by some margin. At a guess 60lbs or so. If we both have the same number of meals a day then my per meal requirement MUST, all other things being equal, be more than his.
There is, for the OP, a search function on this site. It takes the same time to enter the topic into it as it does to post. Google will also show you just how many times the question has come up on a weekly basis. But. like I said above, simple logic negates the need to ask. Pretty much every meal with meat you EVER had out, including a Big Mac, has more than 20g of protein in it. You didn't die, you (more or less) managed to digest it and you'll still able to post lol.