Actually, the ratio of facts to errors in that song (regardless of “perspective”) is about 1:3 or 1:5. It certainly brings up points that it would be well for people to learn about, but its presentation is generally in error.
Regarding this particular set of lines:
Thanksgiving is a fairly common event in most societies. There are many examples of thanksgiving events in the Jewish Scripture, for example.
The specific person mentioned, Cardinal Ximenes (also Jimenez, spellings differ from source to source) was appointed by the pope to be Isabella’s confessor. Once he took up his duties, however, Ximenes actually worked with Isabella to reduce papal authority in Spain, so it is not as if the pope sent him to Spain for the purpose of attacking Moors. He was, however, an idiot who rejected his predecessor’s attempts to convert the Moors of Spain to Catholicism by example, preferring to force it at swordpoint, an attitude that led to an uprising among the Moors, both those who had become Christian and those who had remained Muslim. He followed this up with some attempts to invade North Africa, but except for the capture of Oran, he was mostly unsuccessful. Did they call for a feast of thanksgiving at the time of his solitary victory? Probably, but that was no more notable than any number of other victory feasts proclaimed by many people in many eras.
As to the Moors being “Turks” from “Baghdad.” That is simply foolishness. Aside from Baghdad not being the home of Turks, the Muslims who had swept over North Africa were certainly not Turkish. That the Arab groups who came from the East intermarried with the local black peoples on the West coast of Africa giving rise to a people called Moors is true. (The amount of “Arab” or 'black" or other ethnic influence on the peoples is a bit problematic, of course, since they were not actually keeping records on the subject at the time.)
The song’s author might have confused the later Battle of Lepanto with the expeditions of Ximenes. That battle was, indeed, against the Turkish-led Ottoman Empire, (temporarily) breaking a threat of the Muslim Turks against the Christian/Venetian holding on the isle of Cyprus. It was, indeed, wildly celebrated in Europe as evidence that the Turks would no longer be able to threaten Austria and Italy. A significant portion of the fleet was Spanish, which could have influenced Ras in his contortion of history. (Of course, if he related the facts, he would have had to have abandoned his claim that is was a war against blacks–a central point in his lyrics.)
Now, there were cases in Europe of “turk” being used as a general adjective for Muslim (just as in some Muslim regions “frank” was a general-purpose adjective for Christians). When the first turkeys were imported to Europe from the Americas (they originated on the west side of the Atlantic), they eventually picked up the name turkey-cock that had previously been used to identify the guinea fowl (that was, itself, imported from Muslim lands). (Without wide publications of books with photos, there are several occasions when “exotic” animals “borrowed” names from more familiar (or more widely reported) animals–e.g., calling American bison “buffalo.”)
However, there is no association of eating turkeys on Thanksgiving to celebrate a victory over black people incorrectly nicknamed turks.