There are so many reasons for kids having food aversions and obsessions: sensory processing disorder, addiction to processed food/sugar, an unidentified food allergy or intolerance, a vitamin or mineral deficiency, gut flora imbalance/over population of bad bacteria, undetected tongue tie.
It’s worth it to rule out any possible medical conditions, while you keep on offering a great variety of food with different consistencies of good/high nutritional value.