Do you see diversity of cultures with different levels of development on the planet as a problem? Because as long as it exists there will be the imbalance

>Do you see diversity of cultures with different levels of development on the planet as a problem?

When a more 'advanced' group use their wealth, technology, medicine etc to control a less developed group - yes that can be a problem.

Do you argue for full isolation and no assistance between those groups you describe?

No.

can you describe how such groups can coexist without isolation so that the more developed one helps the less developed one without a degree of influence and control in some shape or form?

ideally something not too far removed from how the world works today

Groups like MSF go and provide medical without trying to control or religiously convert people.

only contacting each other via humanitarian aid is more isolation than coexistence.

Humanitarian aid also exerts influence, if anything by showing how advanced the more advanced group is. For someone whose religious practice involves traditional medicine or shamanism for treatment, western medicine seems like is obviously a religious influence and control. (It also has issues like alleged bartering treatment for sex or food supplies helping mostly the bad guys with guns)

and you're looking at locals like they are too dumb to reject a new religion. it's a condescending view. locals in Siberia did reject the new religion at first and paid the price in blood, it stopped when they learned to pretend to be Christian and keep their traditions under wraps. the situation seems completely different here.