All people jumped into the water to escape, as well as the smart monkey.

问题的关键在于：as well as 是个“短语介词”，其本意是“besides, apart from”。

as well as the smart monkey = apart from the smart monkey

and 是并列连词，如果用and 的话，the smart monkey 应该跟all people 并列起来：

All people and the smart monkey jumped into the water to escape.

或者单独成为并列分句：

All people jumped into the water to escape, and the smart monkey did it, too.