First of all janabah is the state after emission of semen be it via intercourse (be it legal or illegal), masturbation or a wet dream.
And for leaving this state and being able to pray and worship Allah we are required to perform ghusl:
... And if you are in a state of janabah, then purify yourselves. But if you are ill or on a journey or one of you comes ...
Does touching the maniy (semen) in this case make you junub?
The answer is: No
Evidence of this is what ‘Aisha (rad) said in Hadith Sahih:
Allah’s Messenger (ﷺ) used to wash the semen and then go out for
prayer in that (very) garment and I could still see the trace of the
washing on it. [Agreed upon]
(Narrated by "Bukhari" (229) and "Muslim" (...
To make this as brief and simple as I can, these are the rules regarding this issue:
Every thing comes out of penis (Except semen) is Najis (you need to wash your clothes off it, in case any of it spelled on them.), and they require only wodo.
Semen is the only non Najis emission, but you need to do a full body ghusal after it, in case the semen came out ...