Can you kindly give any references from the Holy Quran or Hadiths which allow us to give titles given to Masoomeen (as) such as 'Ayatullah' to ordinary people instead please?

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There are no such titles given to them neither in Quran nor Hadeeth.
These titles are recently invented.
Yes, the title of Ayatollah is given to Imam Ali as mentioned in dua eleftetah, which is recited during the holy month of Ramadan.