Is it true that the flood which occurred to the people of Noah submerged all the peoples of the world, even though the call of Noah, peace be upon him, was not to the entire world, and if so, why did all the peoples of the world suffer?

Allah saved Noah and the believers with him from the flood, and made Noah's descendants the only human survivors. The Qur'an explicitly states that Noah was sent specifically to his people, and divine revelation does not indicate the existence of other peoples besides Noah's people at that time, or that the punishment affected anyone else.

Regarding what is mentioned in the Prophet's ﷺ hadith: "Every prophet was sent specifically to his people, but I was sent to all mankind," the matter suggests that Noah was sent only to his people, who at that time represented all the inhabitants of the Earth. Therefore, his prophethood was specific to his people, yet general in its scope due to the absence of anyone else.

The established principle is that Allah does not punish a people until after sending a messenger to them to establish the proof against them. Muslims are commanded to adhere to the clear, decisive texts and avoid following the ambiguous ones.