Using "that" instead of "who", as a relative pronoun?

There is a subtle difference in meaning.

That - is more general, about ‘musicians in general’.

Who - is more personal - about ‘that particular musician’.

Use ‘that’ (in this example) when you want to go on to talk about musicians.

Use ‘who’ (in this example) when you want to go on to talk about this particular musician.

Examples:

General ‘that musician...’ - The musician that won the award is very creative. He is one of a group of musicians that appeared in the Venice Biennale.

Specific ‘the musician who...’ - The musician who won the award is very creative. He often uses a special guitar with dingly bells fixed on it and sings in a high-pitched monotone.

The lack of understanding of this subtlety, has led to the idea that ‘that is for things and who is for people’, which is not the case.

https://grammarist.com/usage/that-who/