One of the difficult things for us moderns to understand about the past is the centrality of inherited status, which sometimes seems to determine everything; but on the other hand the way some men rose from humble beginnings to the heights of power, without that every undermining the fundamentally hereditary nature of the system.
The best book I know for understanding how this worked is Hillary Mantel's trilogy on Thomas Cromwell. Read them, and you will learn more about the interlocking workings of birth, patronage, ability, effort, and status than you could from a stack of worthy books on Tudor governance.
The first point is that the only way for a humble person to rise in an aristocracy was through patronage. To rise, you had to be lifted up from above. You had to serve. And this service was not to an abstraction like the state or the church, but to some particular person, some patron who would recognize your efforts and reward them. To rise, you became the man of another man.
Thomas Cromwell rose in England as the man of Cardinal Wolsey, the chief minister of Henry VIII's early years on the throne. He dedicated himself completely to the Cardinal's service, faithfully executing every command, taking the Cardinal's part in every quarrel. This meant he was hardly every home, but was constantly waiting on the Cardinal, or doing his business from one end of England to the other. One reason why the great wanted servants of humble background was that men of high birth were less willing to be at a lord's beck and call; they had their pride to consider, and their own lands and households to look after. A nobody like Cromwell could render service a lordling could not, especially if he had Cromwell'a astonishing work ethic.
To be a great man in such a society, a lord needed followers. Some might come to him by old family connections, but others he must find and promote. A powerful minister like the Cardinal needed many assistants, and his own rise or fall would be determined partly by the work they produced. A great lord therefore needed to be as much as anything a judge of talent. Wolsey was in this superb; many of the great men of Tudor England started in his household, chosen and trained by him: Cromwell, Thomas More, Stephen Gardiner, and many more. Cromwell eventually became a great man partly because he also excelled at this; of the young men he brought into his household, who figure as key character's in Mantel's story, two eventually became Chancellors of England and another the Lord Privy Seal.
Notice what happened to the Cardinal's men after his fall from power and death. The Cardinal's enemies did not scorn them because of their association with the Cardinal, but recognized that they had been simply the Cardinal's servants, not at all responsible for the Cardinal's policy. Those that were known as the ablest and most loyal were scooped up by other lords, and the most impressive (Cromwell, More, Gardiner) were taken on by the King. The same happened to Cromwell's men after he fell. To rule required able men to do the hard work of governing, and men who would and could were valuable no matter their backgrounds.
But power, of which Cromwell eventually accumulated a great deal, was not the same thing as high birth. The great hereditary lords never liked Cromwell, and let him know it; they scorned him for an upstart. Hillary Mantell's Cromwell feels keenly his ambiguous status. On the one hand he strives to imitate the old lords, for example building up a fine stable of hunting horses and hounds even though he very rarely hunted. His greed for land was famous. On the other hand he did not pursue certain other lordly activities, most notably war; when it threatened he stayed in London raising the money while lords of old chivalric families led the troops. He had more exalted hopes for his son Gregory. The son was raised to chivalry rather than business, and studied jousting and French rather than accounting. Indeed the son was so successful at becoming a much admired knight that when his father was beheaded he was spared and eventually made the first Baron Cromwell, starting a long line.
This was a major part of what power meant, in that world: being able to choose the best servants and raise them up. To reward them with money and land, to defend them against enemies, to direct their efforts. But never, ever regarding them as your equals.