Chimpanzees are apes, not monkeys.
All Homo, including Homo sapiens humans, belonged to the “great apes”, Hominidae, in which the extant species gorillas, chimpanzees also belonged to. (The “lesser apes” are gibbons.)
The split between monkeys (or more precisely Old World monkeys) and apes (which would include the great apes, hence humans too) occurred 25 million years ago, not 300,000 years ago.
Second, the Homo heidelbergensis didn’t split from the other great apes.
Homo heidelbergensiswere themselves directly descendants of the older Homo ergaster species.
The descendants of Homo heidelbergensis include the Homo neanderthalensis and Homo sapiens.
There are some problems with the classification of Homo ergaster, as to whether it is distinct to the Homo erectus, or they are the same species. But that’s really above my head, so until the palaeontologists can agree and settle with the ergaster and erectus issues, I cannot know if one is true or the other.
But older than both erectus and ergaster, is the Homo habilis, perhaps the oldest of the genus Homo.
If I remember correctly the split between Pan and Homo occurred 6 or 7 million years ago.