Can you share where/how you confirmed this? If the answer contains the name of any of the LLM bullshit engines, then you now know why this forum has a rule against using them for answers… they often produce plausible-looking configuration that contains significant flaws that are not obvious to many users.
As far as I am aware, there is no core Template Humidifier integration.
There is a core integration Generic Hygrostat which is configured under its own top-level key, generic_hygrostat; and there are two custom integrations Humidifier Template and Switch Humidifier (which hasn’t been updated in 4 years), that can be configured under the humidifier key.
None are configured under template.