إِنَّ زَيْدًا قَائِمٌ
Translation: Indeed, Zayd is standing.
إِنَّ: indeclinable emphatic, accusative-governing particle, with no syntactic case position.
زَيْدًا: ism inna, accusative with visible fatḥa.
قَائِمٌ: khabar inna, nominative with visible ḍamma.
«زَيْدًا» is not an object, and «قَائِمٌ» is not a new mubtadaʾ here: their roles come from the inna construction.