Asalamu 3alykum
Dear Naeem Xapha
Although I do see that the Quran does capture that messengers did indeed claim or declare that they were messengers of God, this does not mean that every person who God recognizes as a messenger of His had to declare it. I think this is what is meant by
"There is arguably no direct evidence in the Quran that a messenger 'must' declare himself as a messenger of God".It may also be plausible that those who work for the sake of God spreading the truth and seeking His approval maybe in the sight of God messengers and they do not perceive it. Just because the Quran does not mention certain messengers does not mean that no other messengers walked the Earth. As a matter of fact God makes it clear that some messengers are not related to Prophet Muhammad.
To me this seems to point out that a lot has happened in the span of time and we may not always be able to hear about every person who God recognizes as a messenger.
40:78 We did aforetime send messengers before thee: of them there are some whose story We have related to thee, and some whose story We have not related to thee. It was not (possible) for any messenger to bring a sign except by the leave of Allah: but when the Command of Allah issued, the matter was decided in truth and justice, and there perished, there and then those who stood on Falsehoods.How were messengers of the past recognized as real messengers by their respective community anyway?
Would Saleh, Shuaib, Hud, Lot, Zakariya, Yehya and all the messengers(pbut) have been recognized today if a Scripture was not written about their stories? Its possible that in many cases it was not until after their demise that people recognized them as real messengers or not until God revealed a Scripture about them.
If it was not for the Quran to verify their authenticity for us today, how was the people able to recognize the messengers authenticity? Was it not the truth they were speaking?
It was not all the time messengers had come to their people with miracles. There is instances that some nations had two or more messengers and all they did was make evident the transgressions of their respective community and were only responsible for clear communication.
36:17 "And our duty is only to proclaim the clear Message.". Please see 36:13-30
Although some messengers of the past did come with signs, we know that God has stopped sending sign/miracles to the people.
17:59 And nothing has prevented Us from sending signs except that the former peoples denied them. And We gave Thamud the she-camel as a visible sign, but they wronged her. And We send not the signs except as a warning.So that brings us to the fact that a true messenger is one that imparts truth to its people without also seeking any reward from anyone other than God.
We must also recognize that messengers are not perfect. Some may of had warrants against them for past deeds. (Moses for example).
Also I'm sure you will recognize that there does seem to be a benefit and blessings every time a messenger does pop up amongst a community.
Even today with a protected Scripture from the Almighty there seems to be people in dire need of clarification and making evident to them the truth in their Book. This at times is so liberating and comforting. This is of course is a blessing by the Almighty Lord.
You said
Surely that clears the path for anyone to stand up and declare himself to be divinely inspired.
Arguably brother it has always has been that way. There was nothing stopping anyone to do that before prophet Muhammad anyways. Many possibly claimed inspiration while they were never inspired and yet they were followed. As we know many were indeed divinely inspired and yet were not followed. How can one draw the line between who is who? Truth stands clear from false.
Truth does indeed stand clear from the false. It was that way in the past and will remain like that God willing in the future.
Anyone who speaks truth Insha'Allah will be recognized. How God wants to label that being is up to Him. We might be surprised on the Day of Resurrection who where the messengers who were rehearsing the revelations and warning mankind of the meeting of the Day of Judgement.
39:71 And those who disbelieve are driven unto hell in troops till, when they reach it and the gates thereof are opened, and the warders thereof say unto them: Came there not to you messengers of your own, reciting to you the revelations of your Lord and warning you of the meeting of this your Day? they say: Yea, verily. But the word of doom of disbelievers is fulfilled” does anyone have any evidence of people who could have been legitimate messengers, following on from the Prophet?
Before I could think of answering that, I like to think about it this way:
I ask myself how would I of noticed or recognized prophet Muhammad as being a messenger of God if I was one of the people in his community?
How would I of notice or recognized the messengers in the time Aad, Thamud, the example given in 36:13-30 if I was to be living in their community?
I'm not saying to call anyone a messenger, but its more important to recognize the truth and help anyone who seems to be spreading the message. The point being that God The Most Merciful always guides and warns humanity, reminds and takes people from darkness into light Insha'Allah.
Those are my thoughts
Salam