I believe the structure was used to attract predators. These hominids were evidently living during the harshest period of the last ice age and food was probably scarce. Non-predatory species can be tricky to catch, but predators can be easily attracted given that when you catch and eat one you’ll attract more by the smell of the flesh. I believe they were confident in their ability to catch prey of all sorts.
The presence of flint-napped tools, a variety of bones of both predatory and non-predatory animals, some articulated some not, remnants of fire all suggest to me that these hominids planned to attract predators by the smell of rotting flesh and then kill them for food. The lack of abode-like materials further supports this idea because you wouldn’t want to stay there all the time, but rather camp there when ready to wait for prey, hence the fires. What doesn’t necessary fit with this plan is the overabundance of mammoth bones. Mammoths certainly wouldn’t have been attracted to the smell of rotting flesh. Moreover it would have been quite toilsome to carry from wherever the bones and flesh of mammoths so they could be used as bait for predators.