The reason I don't like to assume they're hominids is because we don't have enough evidence to make that claim.
Convergent evolution might explain all their physical similarities (and differences) to us. Look up the work of Erik Trinkaus or Thomas Berger for more detailed info about Neanderthal anatomy and injury patterns. Here's one brief example -
https://www.sciencedirect.com/science/a ... 0395900136
It seems they were often in close proximity to large ungulates (while hunting) and their injuries were similar to those of present-day rodeo riders.
This doesn't mean they didn't
use throwing spears or that they couldn't
- just that we can be reasonably sure that they used heavy spears for getting in close to their prey and stabbing it. In order to do so they'd have needed organisational skills, teamwork, and the use of language to communicate strategy and ideas as well as the skills to make the tools.
Neanderthals were uniquely adapted for the cold, as modern Inuit people also are to some extent, but they weren't the muscle-bound brutes of modern folklore. They weren't physically incapable of running, for example, or throwing overarm. They were heavily built and had larger brain cases, but there's not much we can infer from those facts about their behaviour. We just don't know.
During the Mousterian period, the same tools were being made by anatomically modern humans and by Neanderthals.
There's so little we really can conclude - beyond the fact that people continue seeing Yowies. As to their exact nature...I wouldn't want to make any definite claims. If a mongoose can evolve to look and behave like a big cat (the Fossa of Madagascar), then another type of mammal could evolve to walk upright like we do. They could even evolve human-like intelligence.
It's long been suggested that the reason humans became avid tool users and builders of structures is a direct result of our physicality - having developed dexterous hands which we didn't need to use to walk, we began using them to make things which stimulated intellectual development, etc. There are those who argue that intelligence came first...but Chimps and Orang Utans use very basic tools and Chimps use a very basic form of verbal communication when they hunt. They also have hands like ours. They still walk on all fours, however.
If a creature evolved bipedal locomotion, as our ancestors did, then they might also evolve comparable intellectual abilities. They wouldn't need to be apes, though, in order to do so. Every time an alleged Yowie hair sample is analysed the results are 'inconclusive' or 'unknown'. That could be an indication that these creatures aren't even remotely similar to anything else we know of.
By assuming they have to be apes, or related to humanity, we're giving in to hubris, I feel. There's no way at present of knowing whether or not they're apes of some variety. We know they're hairy so they're most likely mammals...beyond that, I'm not sure we can say too much of anything.