Several thoughts about plot

1. Why was there no relationship between Eric's mother and Ariel... Really, why doesn't the queen know that there is a maiden in her castle with whom her son spends time?
2. Why hasn't the thread that Eric is adopted been developed? Why did the royal family adopt an unknown boy and give him the right to the throne? (For example, in the MCU it is at least made clear that Loki has royal blood from another realm, so it makes sense for Odin to adopt him.)Also, the absence of the king, Eric's adopted father... What happened to him?
3. One dress? Cinderella, Bella, Aurora in live actions had a better wardrobe than Ariel.... Why does Ariel only wear one dress in the whole movie? Then she has a wedding dress at the end? But it also looks modest. Ursula at fake engagement wears a beautiful purple dress... The villainess has a better dress than the heroine....