The foundations of "Christian Spain" were not laid by the Moors. The Reconquista kingdoms (Asturias, León, Castile, Aragon, Portugal) emerged in opposition to Muslim rule and consciously defined themselves against it.
Europe was also not "largely civilized by Amazigh". There were other cultural centers than Islamic Spain such as Byzantium, Carolingian/Ottonian realms, Italy.
Algebra/mathematics had little to do with African Muslims. Indians, Greeks, Babylonians, ancient Egyptians were the main founders.
India: Decimal system, 0, early Algebra.
Babylonia: Astronomy, calculation methods.
Ancient Egypt: Medicine and geometry.
Greece: Logic, philosophy.
Al-Chwarizmi, who is supposedly the "founder of Algebra", wrote it all down, spread the word and added ideas but didn't really invent anything on his own. "Arabic numerals" are actually Indian numerals. The Arabs themselves called it "ḥisāb al-hindī". The Arabs spread it though.
More importantly, all these "Muslim inventions" date predominantly to the 8th and 9th centuries when Islam just started to spread and wasn't even fully established yet. After that, there is a gap of 1000 years of absolutely nothing. "Muslims invented this and that in the 8th century", ironically, is testament to the fact that once Islam fully established itself all progress and inventions stopped coming out of the Arab world.