Blockchain's core question is: "How do people reach agreement without a trusted third party in the middle?" For example, in a bank transfer, the bank maintains the ledger. In an online marketplace, the platform maintains the transaction record. Blockchain instead keeps a copy of the ledger across many computers in the network and has them all verify it using the same rules.
That's why blockchain doesn't place trust in a single person or company — it builds trust on cryptography + consensus + transparent records instead. That said, blockchain isn't always the right choice. For systems where data needs frequent edits, where privacy matters a lot, or where you need the fastest possible transactions, a normal database can be the better fit.
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Blockchain isn't a database replacement. It's a better fit for cases that need trust, transparency, and tamper-resistance.