You have to train your baby to chew, you are right.
Babies I heard have a very 'sensiive learning period' starting from around 1/2 year to 1+ year, when they will be exploring with their mouths and also learn to chew.
During this time, you have to let your baby explore different textured foods, and introduce harder foods that need to be chewed.
After passing this period, if your baby still has not acquired the chewing skill, they may have lots of problems not only with eating, but also with talking because they have not developed strong mouth / tongue muscles.
I have a personal experience - my cousin's girl, was taken care of by helper. She doesn't have time to oversee her helper's cooking for her girl. Even until age 2, she still cooked porridge, mashed food, very soft food. Then, the mum realized it was time to modify her diet, but it was too late. Her girl rejected all foods that needed to be chewed. Now she's age 4+, and still can't chew - any food with lumps, she'll vomit out. She has seen doctors and speech specialists for speech and swallowing problems - they just say 'there's nothing wrong' with her body, but she has not 'learned' how to chew. Not gaining good weight because she's only eating porridge, soft mince etc.
Another friend of mine, taken care of by grandparents, eats porridge until age 2+. Mum brings her to see speech therapist because he hasn't been talking, however can understand verbal commands very swell. Conclusion: her child has weak facial and tongue muscles. Has to go for therapy / exercises to strenghen muscles - like blowing bubbles exercise, encourage to eat more solid foods. After 2 months of therapy, boy finally started talking.
Don't say you're a failure. You have to tell your helper to co-operate.
Cook his favorite food, encourage him to use his own hands to pick up, bring to his mouth, and chew. Ignore the mess, your child has to learn.