the sum of all transactions that particular address has been roughly $3.7 billion dollars in today's USD bitcoin value

Yes, it's like saying that your local bank has handled billions of dollars in transactions, though there are never more than a few million on site.

Is that address a single individual's wallet?

A "wallet" isn't actually defined in the Bitcoin spec, that's generally a term for an arbitrary collection of addresses. This is just one heavily-used address.

Like I said, it's attributed to a mining pool, specifically btc.com, so it's "owned" by those who control that pool (Bitmain, apparently).

Probably no single person has the private keys for that address, for security. It's used exclusively by their automated systems to receive mined blocks and distribute the funds back to pool members.