
Quite a few people seem confused by when humans mastered fire. One group of vegans I occasionally stalk for meme content is convinced humans began using fire around 4000 B.C.E.

Roughly this time period, I suppose
The truth is of course humans have been using fire since before homo sapiens arose, looked to the skies and began to sing tuneful and reflective songs on the subjects of peace, justice, morality, culture, sport, family life and obliteration of all other life forms.
Indeed the earliest attempts at using fire by the genus homo dates back to 1.7–2 million years ago. The earliest evidence of widespread usage of controlled fires by the genus homo dates back 1 million years and this is not really in much dispute. Anatomically modern humans first appear 300,000 years ago.
Yes, this means earlier forms of humans used fire for twice as long as we, homo sapiens, even exist. This means modern humans never had to deal with any problem without having fire. Indeed, our evolution was shaped by having fire in the first place.
We can eat raw meat still of course and often do: many cured meats are eaten raw, steak tatare is raw, sushi is raw fish and so on. We still can do it, but we long since evolved to do something more effecient instead.