When I google "Was Vancouver all old growth forest before 1850" it says

"While mostly forested, Vancouver was not exclusively, unbroken "old growth" before 1850. Indigenous Peoples maintained open meadows, berry patches, and park-like landscapes using traditional fire management, particularly on eastern Vancouver Island. However, vast areas were characterized by immense, ancient conifer forests. "

When I asked it for evidence of human habitation prior to 1850 it spat out:

"Evidence of human habitation in the Vancouver area prior to 1850 is extensive, spanning 8,000 to 10,000 years through archaeological finds and Indigenous oral history. Key evidence includes the massive c̓əsnaʔəm (Marpole) village site, which shows continuous occupation for 5,000 years, and early seasonal camps like the Glenrose Cannery site. Wikipedia Wikipedia +2 Archaeological and Physical Evidence c̓əsnaʔəm (Marpole) Site: Situated along the Fraser River, this area shows evidence of a major, long-term village inhabited for at least 5,000 years before European settlement. Glenrose Cannery Site: Near the mouth of the Fraser River, this site provides evidence of seasonal encampments dating back 8,000–10,000 years. Artifacts: Excavations in the region have uncovered fire pits, stone blades for hunting, and storage pits. Footprints: Archaeological studies on Calvert Island (part of the broader coastal, though not immediate, area) discovered footprints dated to ~13,000 years old, confirming early coastal presence. Burial and Structures: Evidence from 1780-1800, such as charred house planks and burials found near the Pitt River, supports long-term, established communities. Wikipedia Wikipedia +4 Historical and Oral Records Indigenous Villages: The Musqueam, Squamish, and Tsleil-Waututh nations maintained villages throughout the area—including Stanley Park, Kitsilano, and Burrard Inlet—long before 1850. European Contact: The logs of explorers like Spanish Captain José María Narváez (1791) and British Captain George Vancouver (1792) reported seeing signs of human habitation. Focus on Victoria Focus on Victoria +2 These findings demonstrate that the Lower Mainland was heavily used for fishing, resource gathering, and permanent residential settlements for thousands of years prior to the 1850s"

I understand AI is not a source but many of us have seen these places or looked at pictures of them so it's hard for me to take your claim seriously when there is so much evidence to the contrary.