Beehaw is an instance that doesn't allow you to create your own communities. They want a smaller amount of communities that are more active rather than a large amount of smaller, less active communities.
Other instances let you create communities, but that's why I'm on Beehaw. It's a bit more curated and I feel cuts out a lot of noise I don't need.
So yeah, I'd say just use the Sports community if you want to stick with Beehaw but if this instance isn't meshing with you there's no harm in making one in say, Divisions by Zero for example. They allow you to make communities and are federated with Beehaw so people here could still interact.
I'd so go for creating one. As much as the NFL infuriates me, I'm also hopelessly a Vikings fan and would enjoy having a space to engage in those conversations.
Only admins are able to create new communities on Beehaw, and there's already a sports community so there's not really a need for a more specific one for a single sport. Also, I'm pretty sure there are already communities for specific sports/leagues/teams on other instances that you can use with a Beehaw account thanks to the beauty of federation!