The debug file only contains info of each blocks, starting from genesis block. New best is block hash, date is timestamp of when the block is mined (and thus no correlation with your problem) and others already tell itself.
If you have original wallet.dat (not new/the result of overwritten), we might able to dig more information.
I do have the wallet.dat
Im not sure whether it is an old or new one. How can I tell?
All I know is when I open the debug info I get all that info.
Check the date created or date modified of the wallet.dat on your file explorer. But date created usually changed if the wallet.dat is copied.
He bought or he mined? This file could be related to Bitcoin Core wallet and as it downloads the whole blockchain it shows historical blocks.
The story goes he bought bitcoin back in 2009.
He may have mined it by accident? Im not so sure. But he is certain he bought bitcoin back then.
I doubt he mistaken between mining/buying bitcoin (unless his memory is wrong). But anyway this information can't help much.
A bit off-topic, the first bitcoin exchange is New Liberty Standard (
https://web.archive.org/web/20091229132610/http://newlibertystandard.wetpaint.com/page/Exchange+Rate). You might want ask him if he know/remember this exchange.