It's surprising that the quick conclusion is "proto-humans". Couldn't any other animal do this? Half a million years is a lot of time. Couldn't proto-elephants be a bit more resourceful back then?
Almost all known non-human tool use is for obtaining food, afaik.
Other primates use tools, but it's on the level of a stick stripped of leaves to poke into a termite nest (termites crawl on stick, remove stick, eat).
Avians are the other main category; some only have been observed using tools in captivty. Corvids (crows, ravens, rooks) are particularly interesting. New Caledonian Crows will actually bend the end of a tool to make a hook, good for prying out grubs from under bark. Rooks have handled some particularly complex problems in captivity.
There is no evidence of any non-human doing anything like making axes, chopping wood, and constructing something. If I understand the paper correctly, the 'axes' were 'handaxes' - archaeologist-speak for an unhafted axes, i.e., axes sans handles, i.e., effectively just the axe head which you hold in the palm of your hand. Our ancestors took > 2 million years to figure out how to attach tools to hafts, succeeding by ~200,000 years ago (but only in one place - 'the future is here, it's just not widely distributed yet'.)
Perhaps not even an animal. I could imagine several scenarios where a perpendicular placed log could rub back and forth across another log creating a notch over time.
I guess it comes down to tool marks on the logs notched area but the whole thing is so weathered I can't imagine that evidence is crystal clear either. Its worth noting that the other tools, which the article mentions were found at the same site, are ~100k years younger.