Fullbore target rifle shooting requires virtually no physical exertion yet is considered a sport. Chess requires skill and involves competing yet is not considered a sport. This subject has certainly been discussed before and I have come to the following conclusion- There are many things that very obviously aren't sports and many things that very obviously are. However there are also many things that could either be considered sports ot not considered sports because of the lack of clear definition (both dictionary and common usage) for the word "sport".
Ok, let's look at a bunch of definitions of the word sport and see if cubing falls under most of them.
1.Cambridge Dictionary: 'a game, competition or activity needing physical effort or skill that is played or done according to rules for enjoyment and/or as a job.' I think cubing falls under this.
2.Merriam Webster: (ngl this made me laugh a little) ' a physical activity engaged in for pleasure' ehh, I guess this could be cubing, but it would be too easy to argue against since cubing isn’t that physical, so, no.
3.Oxford Languages:' an activity involving physical exertion and skill in which an individual or team competes against another or others for entertainment.' Yes.
4.Wikipedia: Sport includes all forms of competitive/physical activity or games which, through casual or organized participation, at least in part aim to use, maintain or improve physical ability and skills while providing enjoyment to participants, and in some cases, entertainment for spectators. Yes.
Now, there are (give or take) 11 more websites in my search results we could go through, but I need to go and get Corona tested now.