The 2 witnesses are the Church and the Holy Spirit. The Candlesticks and olive trees. Witnesses before God on all the earth
How can that be possible that the Holy Spirit and the Church would be slain and lie dead in the streets of Jerusalem? The Holy Spirit is not something that mankind can dispose of - even for 3-1/2 days. And Christ told us that even the gates of Hell could not withstand the advance of the church in this world.
The specific language you brought up describing the Two Witnesses tells us who they were: namely, "the two olive trees, and the two candlesticks
standing before the God of the earth". This is language that Scripture has used in relation to
the role of the HIGH PRIESTS of Israel. As in Zechariah 4:2 & 14. Zechariah asked who the two olive trees were, and the angel answered, "These are
the two anointed ones, that stand by the Lord of the whole earth." High priests were anointed to that role of near association with God in the temple.
Ezekiel also describes the high priests in this same fashion in Ezekiel 44:15-16, when
the high priesthood in the post-exilic return was being limited to only the family of Zadok. "But
the priests the Levites, the sons of Zadok, that kept the charge of my sanctuary when the children of Israel went astray from me,
they shall come near to me to minister unto me, and
they shall stand before me to offer unto me the fat and the blood, saith the Lord God: They shall enter into my sanctuary, and they shall come near to my table, to minister unto me, and they shall keep my charge."
So, the Two Witnesses were going to be TWO HIGH PRIESTS who would be slain and lie unburied in the streets of Jerusalem, with the people rejoicing to see them dead. This already happened during the Jewish / Roman war period, when two former high priests (Ananus ben Annas and Joshua ben Gamaliel) were murdered during the Idumean invasion of Jerusalem. Their Zealot rivals who had arranged that Idumean attack rejoiced to see those two dead high priests lying naked and unburied in the streets of Jerusalem.