I was expecting something more elegant, like the famous Genesis Block.
The genesis block included only 1 transaction and that's why it was much smaller.
It may be worth mentioning that you can also get the raw data for transactions separately, so that you deal with smaller data.
https://api.blockchair.com/bitcoin/raw/transaction/5e21f549a51036673b6a47b547c9833489098d04f9e7f9815dbbb254df037e96
This gives you the raw data for a single transaction. Just replace the transaction hash with the hash of any other transaction to get its raw data.
To get the raw data of transactions, you can also go to mempool.space and click "Transaction hex" under the transaction details.