Catherine as a young girl showed some interest in music and drawing but unlike a heroine, she didn't wish practise and was not at all proficient in drawing room pursuits.

She appears to have been a most energetic child.
JA mentions sporty interests like cricket, baseball and horseback riding.

I must admit, I haven't thought of Catherine as attention deficient before. True, she lacked patience for piano as do other JA heroines like Elizabth Bennet, yet JA mentions of Catherine 'she could listen to other people's performance with little fatigue'- so she must have some ability to sit and
concentrate.
I maybe wrong but I thought many children don't learn something in books unless it catches their fancy.
Also, the narrator says when she became a teenager, she became a voracious reader. Even novels require some concentration.
Catherine is set up to be a person of no great intellect or as we see during her adventures of much analytical ability either. She is only able to interest herself in immediate circumstances, like many teenaged girls.
I think JA was chiefly concerned to show Catherine is ill-equipped to be a heroine or bluetocking in contrast to romantic heroines. She may not have shown much interest in learning yet she was a normal, tomboyish girl.