Were those real trades, or just the same few people trading back and forth between themselves as part of a pump-and-dump scam?

To me the more likely use seems not a pump-and-dump scam but rather money laundering - get a plausible and legitimate money trail as "capital gains from digital art investment" from some dirty bitcoins coming in from, for example, a ransomware payout.

Have a look at the sales (lower down the page) of say these:

https://www.larvalabs.com/cryptopunks lowest price available $386k(!)

or more detail on artblocks: https://www.nft-stats.com/collection/art-blocks average price $39k

or these: https://www.nft-stats.com/collection/boredapeyachtclub 90th percentile = $168k