My assumption is that the confirmation can only be done by a node and the number of confirmation means total amount of node that have verified that transaction.
If this is the case, will the first transaction of the bitcoin has the highest number of confirmation?
Yes, you are on the right track! The number of confirmations in a Bitcoin transaction refers to the number of blocks following the block containing the transaction in question. Each block must be validated by the network of nodes, so the more successive blocks validate the transaction, the greater the confidence that it has been accepted by the network. However, the number of confirmations does not represent the number of nodes that have verified the transaction, but the number of successive blocks that have been added to the blockchain. The first Bitcoin transaction didn't have more confirmations because there was nothing previous to connect to, but over time and as successive blocks were added, it accumulated more confirmations.