and during my study I read that it is data encrypted design used for data identification and stored all transaction data mined on the bitcoin network safely in blockchain.
1. Bitcoin itself doesn't use encryption cryptography.
2. I'm not sure what do you mean by data identification, since Bitcoin is pseudonymous.
It clear to me from my research that Merkle trees are crucial in blockchain, but I'd like some assistance in understanding what would happen if merkle trees didn't included in the blockchain and what difficulties arise while using them.
What would happen? SPV mechanism would be more difficult and less efficient, since it needs to download whole block which contain relevant TX.