Is it considered a forbidden form of seeking aid to use phrases like "Wa Mu'tasima!" (Oh My Mu'tasim!) or "Aghithuna ya Arab!" (Help us, O Arabs!) in songs about the Palestinian cause?

Seeking aid from a created being in matters they are capable of is not considered polytheism (shirk); rather, it falls under the category of mutual cooperation among people. The two aforementioned phrases fall under this category. However, seeking aid from a created being in matters that none but Allah is capable of is polytheism.