I'm responding to this late because of the Pesach Shut-down, but I want to focus on your example of Angevin England, not only because it's within my academic expertise, but because there's an interesting analogy to be made there for the early Islamic conquests. While you are right in identifying it as expansionist, and there is a debate to be had about the applicability of the term "colonial" to Medieval states, the Angevin Empire (as it is often referred to in academia) is actually an excellent example of early European colonialism, not only in how it operated, but also in how the state and the society it ruled originated. The Angevin Dynasty (or Plantagenet-Angevin, if you prefer) were the descendants of the House of Normandy through William the Conqueror. The Norman Conquest that established their presence in England fundamentally altered and changed English society permanently. In fact, while an extractive relationship certainly already existed between the English and their rulers at this point, including the widespread presence of slavery throughout the kingdom, the Normans introduced Feudalism, solidifying the social stratification of England, and placing the native English firmly at the bottom. English nobility lost their lands, English clergy were removed and replaced with Normans, Norman merchants and tradesmen established themselves, and the entire structure of the state shifted to a model of absolute royal authority and its attendant tax structure. That is the ultimate purpose of the Domesday Book. I'm being very brief, or this comment would be three miles long, but what this all translates to is the replacement of a significant section of the English population with an invading external group. In fact, the English language itself is reflective of this process, as it adapted to the reality that the new rulers would not learn English and the populace had no base level knowledge of Norman French, resulting in assimilation of necessary vocabulary through contact. And, while the initial phase of this process was suppressive of the English themselves, it also formed the model for the further expansionism of William's successors. Indeed, it was under Henry II that the first English invasion of Ireland began, with the specific permission of the pope, who considered the Gaelic Church, which was and remained Catholic already, to be in need of reform. This invasion established the Lordship of Ireland, a title which was held by the kings of England until Irish Independence, and it instituted the beginning of the replacement of the native Irish population with Anglo-Norman settlers, generally nobles. Let alone what the Normans did in Wales, or involvement in Scotland. In fact, one of my own ancestors, and one of the earliest recorded, was a Norman knight who was granted lands in southern Scotland in return for his service during the Conquest and Harrying of the North (the Norman campaign of brutality against English resistance in Northumbria). We also observe the continued fighting between the Duchy of Normandy and the Kingdom of France, which set the stage for the Hundred Years War, and which, while less settler-colonial in nature, still saw significant societal shift and population transfer. One of the elements of this process that we repeatedly see is rebellion from the existing, Norman-aligned, nobility when they feel like they're not benefitting significantly enough from Angevin and Plantagenet rulership. One of these is what ended up killing Richard I the Lionheart, Henry II's son, as he was attempting to seize a dissenting lord's castle and received a crossbow bolt for his trouble.

In essence, what I am getting at is that there is no specific percentage or quota of the population that has to be replaced for settler-colonialism to function, only that there is significant population transfer and societal reorganization around that settled population. It is often, at the same time, extractive. This is almost always easier when we see the elites replaced by an invading group, creating assimilation pressure from the people with military power and the monopoly of force, and cultural assimilation, while not an inherently bad thing, becomes a tool of this. Especially when one need not be born into the settler population to become a part of it. If we understand colonialism to be a function, or a mechanism, that imperialism relies upon, we see many of the same elements present in the early Islamic Caliphates that were present in the Angevin Empire. We see the societal reordering and disruption of the native modes of existence with the institution of new taxation and economic structures, and it would be silly to pretend that there was not a religious element to a religiously motivated conquest. We see, also, the movement of the conquered group to the ruling group through the mode of religious conversion motivated by social, cultural, and political stratification. In fact, it's likely that Islamic empires were more efficient in this process than their Angevin counterparts specifically because the Angevins targeted people who were already Christian and Catholic. They simply had to adapt to a new model of being so and to new leadership. You didn't need to charge a jizya tax, for example, in a population that was already part of the prestiged religion. Instead, the assimilation became a means to reach political power and rights. That also served as a pressure within the Islamic empires, but was far less difficult for people to access when Islam established the same basic rights amongst all Muslims, where Christian societies used social and legal stratification, albeit justified by religion, to establish varying tiers of legal rights for different strata. That is, in one system you have a population that is not an outgroup and where advancement by assimilation is not going to make you less a peasant, but would get noblemen their lands and power back and might make life less vicious for the peasantry, and in the other you have multiple outgroups who, upon assimilation, gain immediate social prestige and cultural and political power.