I only can say that slavery was tried to be forbidden by spanish laws in America, it was accepted (even thinking it as inmmoral) only because of the presion of rich bussinessmen who wanted cheap workers and the presion of Portuguese and English slave sellers who were interested on slavery selling better than paid work in Spanish America and only for african non cristian people, it was forbidden to enslave indians (mita forced working sistem was not a spanish idea but inca one). The problem was that whith the tecnollogy of that time spanish government had too many problems to obbligate criollos to respect the indian protections laws (when Spain's king controll became more effective in XVIII century criollos rapidly started the independence movements offering indians a better life that was a fake for using them in war and betrying them after it).
The destruction of american cultures was littlest in Spanish America than in other zones of the world conquered by europeans (in portuguese Brazil for example). In other way it must be remembered that they acted on XVI century, not in XXI century: was another time and the ideas of that people were not our ones, what they did can be strange or savage for our sensibility but they only could do what was logical or thought as good then. Phillosophy, religion, policy, education were absolutely different, but even so we must remember the high percentage of indian aborigin and halfblooded (sorry I don't know if this is the correct word) population in Latin America in contrast whith No0thern America, Australia or New Zealand. Another historic fact is that great damages to indians were commited not by spanish while the conquest times but by "criollos" (white spanish-americans) after independence. For sure spanish conquistadores were not angels, but nor were demons either, simply were people of their time who did what tey tought was the best for them and their country and religion (just as today do United States soldiers around the world for example).
Winners<img style="display:inline;vertical-align:super;margin:0 0 0 3pxadding:0;border:0;min-width:0;width:auto;height:10px;float:none;border:0;outline:0" src="cdncache1-a.akamaihd.net/items…"> every time think they're doing good, and loosers every time think a great injustice has been commited to them. Spanish and aztecs surely thougt so, but we must be scientific when we study the past and know there were no "good and bad guys" as in films but people in both sides who were doing what they believed to be correct. We can't judge them under our times' parameters, they had not our knowledge nor ideas of human rights or respect for other cultures.
And about humility I must say you that today, the problem of spaniards is just that we remember too well the times we were defeated and notso often the great victories of our ancestors (not only in America, but in europe, in Africa, in Oceania and in Asia), so we have lost many (too much in fact) of our national pride. They did things that damaged other peoples or cultures? Yes, we know and we are not fond of it, but we can't undo what they did. But it must be remembered too that if Spanish had not conquered, maybe northern europeans whith still less respect for indians would have and today the problem of indian cultures only was going to be search on archaeological sites and documents for their records, whithout survivors and descendants who had conserved part of their languages, and traditions.
Greetings from Spain.