Bridgwater, 33, had "failed to allow sufficient room" to overtake Mr Humphreys which led to the near-side headlight colliding with the handlebar of the bike, a court heard.
Mr Matthew Barnes, prosecuting, told Wolverhampton Crown Court police believe the near-side wing mirror of the Mercedes van struck Mr Humphrey's head.
Investigations by police had scientifically calculated the overtaking speed of the vehicle to be 34mph, higher than Bridgwater's initial estimation of 25mph to 28mph.
The collision happened on the cross-roads of Temple Bar with Harper Street, on the left, and Leveson Street, on the right, at 10.15am on a clear and sunny morning, a judge heard.
Mr Barnes added Bridgwater, who was 32 at the time, was arrested at the scene after testing positive for cannabis and was later found to be over the legal limit for THC, registering at 2.5 micrograms against the legal limit of two micrograms in his blood.
The defendant, who was interviewed by police on June 6, said he was a delivery driver and had never driven down Temple Bar before – having started his shift on the day at 5am.
Bridgwater, of Lichfield Street in Stourport, told officers he went to bed at 11pm the day before and was up at 4am but felt he had "significant" sleep – and that he believed he "significantly manoeuvred" his van to avoid the cyclist, but was made of aware of Mr Humphreys' injuries after hearing a "thud", a judge heard.
The defendant stopped immediately, tried to take the pulse of the cyclist and screamed for help – before having a panic attack which led him to return to his van after the emergency services had been called.
Bridgwater admitted to police he had been a daily cannabis smoker for a long time, smoking at night to help him sleep, and informed them he had "one spliff" the night before at 9pm – but he believed the effects of it had worn off before he woke up, a judge heard.
Mr Humphreys, from Willenhall, was taken to Queen Elizabeth Hospital in Birmingham after the collision to be treated for multiple skull fractures, multiple facial fractures and fractured ribs, and was placed into an induced coma.
On June 17, he developed pneumonia and on June 25 a decision was taken by his family – after being advised by doctors he could not be saved– to agree to withdraw his breathing tube. He died the following day at 11.27am.
Mr Humphrey's son Ian, who lives in Australia, had his statement read out to Wolverhampton Crown Court and described his father in it as the "strongest man" he's ever met who was "so alive" and the life and soul of any get-together.
Mr Humphrey's had encouraged his children to be hard workers and Ian, his son, had thought his father had "lived to work" but later realised his father "worked to live", a judge heard.
Ian, in his statement, said the news had come as an "emotional shock" which he couldn't find the words to and, because of Covid-19 restrictions and other complications, he was unable to say goodbye in person – which he described as the "hardest decision" of his life.
Mr Barnes, reading the statement, said on Ian's behalf: "I had to say goodbye and watch my father pass away via Facebook – to not be able to be with them [his family and his father in hospital] was so painful and the funeral restrictions made things so hard as well."
Other statements were read out by two other members of Mr Humphrey's family – his daughter and granddaughter – who described him as a "social butterfly" and said his death had caused an "astronomical" impact on the family.
Alexander Pritchard-Jones, defending Bridgwater, said the defendant is "devastated by what he has done" and "beats himself up" about it every day. He has suffered "significant" anxiety since the incident, has stopped taking cannabis and has shown genuine remorse for his actions.
Mr Pritchard-Jones said the 33-year-old, who was hard-working and a man of good character, now accepts he had been travelling at 34mph as the police had concluded and had indicated he would plead guilty at the first opportunity, which he did, a judge heard.
Judge Simon Ward handed Bridgwater, 33, of Lichfield Street in Stourport, a sentence of 18 months in prison at Wolverhampton Crown Court on Thursday.
The defendant had previously pleading guilty to causing death by careless driving while over the prescribed limit for drugs at a hearing on May 27. Bridgwater was also disqualified from driving for two years and is also required to take an extended driving test.