how did the Mahdi's political islam impact future currents of thought and events in the islamic world that would have touched on
On some level i'm pretty sure i understand why Qutb is seen as the originator but i'm always a little bit bothered how this narrative seems to place him outside of the events of the late long 19th century. Did they just not have a big impact?
Largely, it's because the Mahdi state in Sudan deviated from core Islamic beliefs in theologically significant ways, so it's harder to draw a direct inspirational link between contemporary political movements that claim to draw legitimacy from Islam, and the particular practices of Mahdist Sudan.
In particular, let's look at one Islamic practice, the declaration of faith.
The declaration of faith is the set of words that are uttered by anyone who seeks to declare their conversion to Islam. It's remained basically stable throughout Islamic history, and goes roughly as follows.
"(I bear witness that) there is no God but God, and Muhammad is the messenger of God".
Islam takes its monotheism very seriously. Shirk, or making partners with God, is known to be the one sin that God does not forgive. This is why, for example, you see lots of verses in the Qur'an that are rather unkind to polytheists, whereas Jews and Christians (a reference to monotheist Christians that were the most significant presence in the area at the time) are respected as "People of the Book" and assured entrance to heaven, etc.
Sudan's leader decided to innovate on this important line, adding this bit at the end,
Muhammad Ahmad is the Mahdi (guided one) of God and the representative of His Prophet
It's fairly common practice over history for megalomaniac Muslim leaders to declare themselves Mahdis, for various reasons that are readily imaginable. Future Muslims, however, tend to view innovations on the core tenets of the faith, such as the declaration (or shahada) rather unfavorably. Especially when the self-proclaimed "Mahdi" dies soon after, and the prophesies are shown to remain unfulfilled.
Qutb didn't declare himself to have a particularly special relationship with God. But he did create a pseudo-intellectual justification for offensive warfare that was and is appealing to contemporary factions interested in theological justifications to create war. The man died, but his ideas live on. Hence, Qutb is more properly one of the fathers of this particular spin on Islamic thought.
Look at these great texts for more information:
From Secularism to Jihad: Sayyid Qutb and the Foundations of Radical Islamism by Adnan Musallam
and
The Formation of the Sudanese Mahdist State: Ceremony and Symbols of Authority:1882-1898 by Kim Pearcy