I find the concept of Jihad really confusing, since there seems to be a great deal of misinformation about it in my social cycle. What the Jihad meant when it was born, back in the early years of Islam? Is the Jihad of today the same as the Jihad of this period? If it is, then how come a religious idea last for so long? If it is not, then how it changed?
Sorry, to be clear, your top question is about "Islamism" which is generally defined as an ideology seeking to incorporate Islam into modern politics and which emerged in the late 19th and early 20th centuries.
The explanatory text of your question seems to be asking more about what the role of Jihad is in the Islamic faith more generally and over a much longer period of time.
Both are intelligible questions and are somewhat related, but I just want to understand which is your greater area of interest. I.e. do you want to know what the relationship is between Islamist movements like The Muslim Brotherhood and jihad, or about the history of jihad more generally?