1. What is Auli-Ibrahim?
Auli-Ibrahim is a higher type family, in which the kinship is due to:
(1) They are on a mission together to guide humans.
(2) They ascend together in heaven/sky
(3) They are on par with each other in rank
(4) They are blessed together and purified together one purification and level of blessings.
(5) They are related by blood as well
2. The comparison
The "do you envy..." is means of comparing, comparing who "the humans" with who? The comparison is with Ahlulbayt of Ibrahim (a) meaning the humans too are an Ahlulbayt chosen by God. Allah (swt) could've just said "Messengers" but instead emphasized on a chosen Ahlulbayt of the past, to show, this is what we are given too.
3. The Contrast
"do you envy" is also a contrast, with the authority of leaders of people of the book, with that of the humans envied and Ahlulbayt of Ibrahim, in this regard, the subject is about religious leadership and authority. The "Do they have a share in the authority?" is a rhetorical refutation that this authority is something that other than God decides... so the context is divine Authority.
4. The emphasis of obeying God
In flow with that, is the emphasis to obey God showing obedience to the Rasool and Ulil-Amr is obedience to God.
5. The "from you" has a flow with Ahlulbayt of Ibrahim and their authority.
The from you is obviously saying, you too have been given an Ulil-Amr. And if we think about it, Ahlulbayt of Ibrahim are an Ulil-Amr as well.
This saying, you too have been given an Ahlulbayt that is given authority by God so obey God and obey them.
6. The Ayatallah and faith context
In addition to all this, is that the emphasis with respect to the envied humans, is to believe in Ayatallah and not turn away from the Authority vested in his chosen, in flow with that, is 4:59. The obedience to Ulil-Amr is clearly an issue of faith and submission. It's clear also by this emphasis to have faith in God's signs.
7. The witnesses
In addition to that, before getting into dialogue of the opposition of the people of the book to the envied humans, the Quran talked about the witnesses and for every people there is a witness from them, this flows also well to the Ulil-Amr, it's part of what gives it context by flow. It's obvious the Ulil-Amr are witnesses.
8. The great Authority
The great Authority is obviously one and the same that the Ulil-Amr are given and Ahlulbayt of Ibrahim were Imams who guide by God's command.
9. The obedience to all Messengers by God's permission
After that, there is emphasis that all Messengers were to be obeyed by God's permission, this again, is in context of divine Authority.