Yes Rama,
It is possible! By granting Create Rights, you will not be able to stop users from editin the instances of a custom object, but there is a work-around.
1. Create a Custom Object & Grant Create Rights to the users via Group
2. Configure the List Layout in such a way that all the important fields of the Custom Objects are listed in the ist Layout Itself
3. Remove any link from the List Layout which will take the users to the Edit Layout, this will stop the user from viewing the Edit Layout, which means you are blocking the users to edit the attributes from the Edit Layout
4. Now uncheck the "Allow Editing" checkbox for all the attribute from the "Object >> View >> List >> Field" screen one by one
Now the users will not be able to edit anything from the list layout neither will they be able to access the edit layout.
If you insist to keep the edit layout open for the users, there is another way,
1. Make the Custom Object "Event Enabled"
2. Create a process on the Custom Object which Auto-Starts on Creation of Instances
3. Create an System Action inside a step with option "Lock All Attributes"
As soon as the user hits save in the Create Layout, all the attributes will be locked and hence the users will not be able to edit any attributes.
Let me know if this helps!
Regards,
Mathan