For a toddler who has just begun to speak, is Hindi easier to speak as compared to English?

There are several parts to your questions.

1. Is Hindi easier to speak for children? No. All languages are about the same level of difficulty for children.

2. How come the child is learning even when she is getting less attention from adults? Adults are only one source of language learning for children. Sometimes not even the main one. She is likely learning as much from her peers as from the teachers.

3. Why is the child less willing to use English? This very common with languages that are 'put on' by parents who are not its native speakers. The child learns some of them passively but sees that nobody else is using that language for achieving important things (from their perspective). It's made worse by the child knowing that the parent can understand the other language/

4. Children in bilingual situations often go through stages of skill in either or both of their languages. Their two languages are never perfectly balanced. So this could just as easily be just a phase.