Jains and Hindus
Let me shed some insight on this topic.
Traditionally in India there have been two main samskriti's. They are
Vedic and Shraman. The former is basically based on Vedas and we can put
all the hindus (I consider's sikhs also as hindus) for all purposes. In the
latter case we can put Jains and Buddhists. The term Jain and Hindu are
modern terms. The term Jain bacame popular from the times of Mahvira, the
last tirthankar (quivalent to Guru, God but a different word. More closer
to Buddha). There hve been 24 of them, with Rshabha, the first one.
The Vedic samskriti believes in Vedas, God etc. The Shraman's belief in
self/Atman. They belive that you have to do Shraman (labour) to enlighten
yourself and no body is sitting anywere to please (like Surya, Vishu etc
mentioned in the Vedas). Although this seems quite similar to Vedic
samskriti too as you have to do Shraman (like meditate, Yajna, devotion, etc)
to please the lord. However in Shraman there is no pleasing. It is the
pure enlightnment of the self without setting your Dhyana on any external
entity. There is no reward or punishment. They believe is atam
(in cuurent form ) to transform in to parmatam (the highest form of the soul).
The existence of Swarga, Narak, Devatas (including Shiv, Brahama,
Vishnu, Mahesh etc) is accepted in Shraman but it is said that by praying
them it won't help you to become param atma.
The Shraman hence don't pray as such to these Gods ( a non-Shramn
term) but the Gunas. They say that if a particular atma (whether you, me or
Brahma) is in the purest form (marked by Gunas) then we pray you. They
believe that there have been 24 tirthankara in the current kala chakra
on Earth who have atttained this state. They also believe in so called
Siddhas, whose number is innumerable who have also attained this state but
have not preached the Dharma.
That's it. I think the above beliefs of Jains gives enough room
to judge whether you put them under term Hindu or not.
I would like to add that the current form of Jains has been heavily
influenced by the method of religious practices of Hindus.
Please read Jain and Hindus above in quotas.
Hope this helps in clearifying your doubt.