Does the Humanoid and Infected % damage get stacked against zombie and boss ?

If you're referring to food buffs, it is a No (Humanoid & Infected %) as you can only gain one food buffs at a time. However eating the same food buffs can be stacked as it prolongs the time but has the same effects.

Example: When you eat Sandwich you get the DMG to Infected % buff, but when you eat another food Minced Meat you will now get the DMG to Humanoid % (two different food does not stack at each other)