Does Bitcoin no longer fulfill its original purpose? The Bitcoin whitepaper details &quot;a purely peer-to-peer version of electronic cash&quot;, usable for &quot;small casual transactions&quot;.
According to BitInfoCharts, the average Bitcoin transaction fee is currently 58 USD.
Is Bitcoin no longer usable for its original purpose of being a peer-to-peer version of electronic cash?
Does Bitcoin no longer fulfill its original purpose?

It does. Original purpose included decentralization and censorship resistance which still exists. I did not start researching about Bitcoin because I found a new way to transact online which is quicker and cheaper than my bank transactions, I started using Bitcoin for different reasons. So I assume things can be different for everyone and one whitepaper cannot include them all. Whitepaper is not a Bible and Bitcoin is not a religion. Bitcoin is a software (protocol for decentralized network in which you don't trust anyone) that is evolving every day.

The Bitcoin whitepaper details &quot;a purely peer-to-peer version of electronic cash&quot;, usable for &quot;small casual transactions&quot;.

It's still peer to peer if you run full node, it's still electronic. Small casual transactions work better using layer 2 and it's not difficult to understand that things can scale in layers.
There are layers in almost everything we use in computers and this approach is not limited to Bitcoin scaling.
If everything has to be done on-chain and every full node needs to sync it, do you think everyone will be able to run a full node? Did the whitepaper mention that full nodes do not matter and they can be run by few companies in some data centers?
What will you achieve by spending $10 on a coffee with low fees if you can't run your own full node and trust someone else?

Is Bitcoin no longer usable for its original purpose of being a peer-to-peer version of electronic cash?

It is usable and people who have been following Bitcoin development are using layer 2 solutions like Lightning Network.
Recent example: Okex supporting LN for bitcoin deposit/withdrawal