Phrase for insatiable with positive connotation

Is there a word or phrase with a positive connotation for someone who is never content with their standings, quite curious and always pushing for new heights?

I'm not sure this is close enough in meaning to the word or phrase you're searching for, but perhaps indefatigable would serve?

Such a person can be described as being not content to rest on their laurels. This certainly has a positive thrust: the attitude of aiming ever higher.

not rest on your laurels [COMMON] If someone does not rest on their laurels, they continue working hard to make sure that they continue to be successful rather than relying on the success they have already had.

Derivation: In ancient Greece, the laurel or bay tree was associated with the god Apollo. The winning competitors in the Pythian games, which were held in honour of Apollo, were given crowns or wreaths of laurel.

• We will not rest on our laurels. There is still much to be done.
• He never rested on his laurels but continually evolved as an artist.

[Collins COBUILD Idioms Dictionary, 3rd ed]

The expanded version is also common; here are several examples from the many to be found on the internet:

• Not content to rest on their laurels, Club President Sara Burbine Potter '91 and her dedicated Board of Directors forged another spectacular year ....

[Dartmouth Alumni]

• At Freed, our consultants are not content to rest on their laurels. Instead, they pursue ongoing professional development activities to enhance and hone their ....

[Freed Associates]

• But now, not content to rest on her laurels, Rowling is back for more. Her novel for adults, "The Casual Vacancy," was published last year.

[The Christian Science Monitor]