Yes, a singer/musician can stand up and deliver a blues, then a Scots ballad, then an Irish jig, then a touch of kletzmer. But isn't this just mimicry?

If the music speaks to the person, then the musician has it from both sides: he/she is entertained, therefore he/she entertains.
I have seen many a solo musician lose the contact with the people, because their eyes are tracing the 'large W' across the venue all of the time. They lose concentration, interest, and later, engagement, in what they do.
They might as well just be having a bad day at the office.

Thank God, I have never had a bad day at the office in about 15-20 years.

I know German people who sing 'Lisdoonvarna' with a Christy Moore accent; Norwegians and Swedish bands frantically trying to 'Out-Shane-McGowan' each other.
... and I know many Europeans who speak perfect English with every accent under the sun from Ireland.

Mimicry?
Some of it is, granted.
A lot of it is not, however

I learned to speak Oslo Norwegian. People still find it hilarious when a County Armagh dialect gets its teeth into some of the sounds they have: 'Æ' 'Ø' 'Å', etc.
That's my roots coming through.

There are also some people whose first exposure to the English language were from the TEFL corps (Teach English as a Foreign Language); Dublin people, Wigan people, etc.

Because we know the language from our own perspective, we don't often question this first exposure people from other countries get.

If it is mimicry, then we all are mimics. Even our children, who will invariably pick up the first language and musical experiences from their area.

I doubt that the natives ever had time to sing play or dance - too busy trying to scrat a living.
Taking that statement to its logical conclusion, no music (especially Blues) would have ever developed.

B.