As a person of Latin American descent from the Caribbean (ouch !), believe me I have a hard time reconciling the atrocities of the Encounter Era as a Catholic.
To facilitate the process, I shall copy, and paste them in order of the year they were issued.
Sicut dudum (1435)
"They have deprived the natives of their property or turned it to their own use, and have subjected some of the inhabitants of said islands to perpetual slavery (subdiderunt perpetuae servituti), sold them to other persons and committed other various illicit and evil deeds against them.... Therefore We ... exhort, through the sprinkling of the Blood of Jesus Christ shed for their sins, one and all, temporal princes, lords, captains, armed men, barons, soldiers, nobles, communities and all others of every kind among the Christian faithful of whatever state, grade or condition, that they themselves desist from the aforementioned deeds, cause those subject to them to desist from them, and restrain them rigorously. And no less do We order and command all and each of the faithful of each sex that, within the space of fifteen days of the publication of these letters in the place where they live, that they restore to their pristine liberty all and each person of either sex who were once residents of said Canary Islands ... who have been made subject to slavery (servituti subicere). These people are to be totally and perpetually free and are to be let go without the exaction or reception of any money."
Dum Diversas (1452):
"We grant you [Kings of Spain and Portugal] by these present documents, with our Apostolic Authority, full and free permission to invade, search out, capture, and subjugate the Saracens and pagans and any other unbelievers and enemies of Christ wherever they may be, as well as their kingdoms, duchies, counties, principalities, and other property ...] and to reduce their persons into perpetual slavery."
Romanus Pontifex (1455):
"The Roman pontiff, successor of the key-bearer of the heavenly kingdom and vicar of Jesus Christ, contemplating with a father's mind all the several climes of the world and the characteristics of all the nations dwelling in them and seeking and desiring the salvation of all, wholesomely ordains and disposes upon careful deliberation those things which he sees will be agreeable to the Divine Majesty and by which he may bring the sheep entrusted to him by God into the single divine fold, and may acquire for them the reward of eternal felicity, and obtain pardon for their souls. This we believe will more certainly come to pass, through the aid of the Lord, if we bestow suitable favors and special graces on those Catholic kings and princes, who, like athletes and intrepid champions of the Christian faith, as we know by the evidence of facts, not only restrain the savage excesses of the Saracens and of other infidels, enemies of the Christian name, but also for the defense and increase of the faith vanquish them and their kingdoms and habitations, though situated in the remotest parts unknown to us, and subject them to their own temporal dominion, sparing no labor and expense, in order that those kings and princes, relieved of all obstacles, may be the more animated to the prosecution of so salutary and laudable a work....to conserve their right and possession, [the said king and infante] under certain most severe penalties then expressed, have prohibited and in general have ordained that none, unless with their sailors and ships and on payment of a certain tribute and with an express license previously obtained from the said king or infante, should presume to sail to the said provinces or to trade in their ports or to fish in the sea,
...since we had formerly by other letters of ours granted among other things free and ample faculty to the aforesaid King Alfonso -- to invade, search out, capture, vanquish, and subdue all Saracens and pagans whatsoever, and other enemies of Christ wheresoever placed, and the kingdoms, dukedoms, principalities, dominions, possessions, and all movable and immovable goods whatsoever held and possessed by them and to reduce their persons to perpetual slavery, and to apply and appropriate to himself and his successors the kingdoms, dukedoms, counties, principalities, dominions, possessions, and goods, and to convert them to his and their use and profit -- by having secured the said faculty, the said King Alfonso, or, by his authority, the aforesaid infante, justly and lawfully has acquired and possessed, and doth possess, these islands, lands, harbors, and seas, and they do of right belong and pertain to the said King Alfonso and his successors, nor without special license from King Alfonso and his successors themselves has any other even of the faithful of Christ been entitled hitherto, nor is he by any means now entitled lawfully to meddle therewith."
True these particular bulls were issued prior to the so called "discovery" of "The Americas", but they later came to be applied to the newly "discovered" lands.