With cash you can hand it to another person in payment. With conventional digital payments you request a trusted intermediary (your bank) to transfer that value to them. What if you don't trust banks but still want to be able to pay people?

Bitcoin was born in the Global Financial Crisis when the world was discovering the massive scam which the financial services industry had perpetrated, causing the whole problem. People wanted a way to do transactions without having to trust institutions which demonstrably couldn't be trusted. Hence Bitcoin which acts like digital cash with no trusted intermediary.