Original estimate textbox not showing for me while creating a new issue but showing validation error while trying to save.
This is not a kanban board. However, when I view old tasks time estimates are shown there.
I have checked project settings, board settings but can't see any thing mis-configured. Even after comparing project/board settings with other projects, nothing useful found.
If the fields are not visible, the Create Issue screen needs to be adjusted for that issue type in that project. That change can be accomplished only by a Jira Administrator.
The setting of the fields as Required may have been done in the Field Configuration as mentioned by @Fernando Eugênio da Silva . That also will require Jira Admin level access to change.
The fields could also be generating that message if a Validator has been added to the workflow to require that data to be entered during issue creation. That again is something that would require a Jira Admin level of access to modify.
You need to review your field configuration:
Go to "Project Settings"
Go to "Issues"
Go to "Fields"
Click to edit the field configuration. Looking for the customfields are present error and you gonna see some information like a tag "required" in this fields. Change to "Optional" and try again.