Know some good easy beginner tunes for fiddle?

Twinkle twinkle little star
Rock a bye baby

The alphabet song (Also known as Twinkle twinkle little star as @njnyjobs said) is usually suitable for most beginner instruments as it essentially traverses the scales up and down.
I always find Amazing Grace is a great song for beginners too.
It’s mainly brass I play but I am learning to play the piano, I can rattle a tune out of the guitar and I have played violin at school.
Some beginners help for fiddle here
And theres a really interesting resource Here – Now, I appreciate this is for Violin but the fundamentals are similar and this may be of use.

Remember the three P’s. Practice, Persevere, Perform!
And Princess Ayla is Adorable.

Start with scales to give yourself a good idea of what the finger positions sound like.

Then learn Happy Birthday.