how the "what" (bitcoin in this case) came into existence.
It's a number, written in on the ledger. Just like how when the fed wants to give a bank a few billion dollars some zeroes appear in their computer.
The way bitcoin works is ALL in the blockchain. Each block consists of:
[data from previous block]
Qzukk gives himself 0.x BTC for solving this block
Bob gave 1.2 BTC to Dave
Sam gave 0.8 BTC to Bob
James gave 0.9 BTC to Bob
[variable data]
In order for this block to be valid, Qzukk has to find [variable data] that makes the SHA-256 of the block be 0x0000000000... (the number of zeroes in the hash is how the "speed" of mining is set. Because of the "Qzukk gives himself x" transaction, everyone is working on a different block (yours would say "gnupun gave himself..."). Furthermore, because of the data from the previous block being used, whoever solves the block and gets it in the blockchain first means everyone else has to start over on the next block, which is why it's pointless for small fry to try and mine now.