David Wilson's victim fell backwards after being hit in the face and banged his head on the road, causing serious injuries that meant he needed hospital treatment for eight days and is still in the care of a community health team 18 months on.
Leeds Crown Court heard the man had been walking to work on November 23, 2020 and was near Fearnville Sports Centre at around 12.45pm when he saw Wilson approaching.
Prosecutor Daniel Penman said the man stepped aside but Wilson started shouting and asked what he was doing.
The man tried to calm him down and offered to buy him a sandwich and drink in a nearby cafe so they could talk it over, but Wilson continued to be abusive.
Wilson then punched the man in the face, causing him to fall backwards and hit his head.
A number of people witnessed the incident, including an ambulance driver who saw Wilson casually walk away as a number of drivers stopped to help the victim.
The court heard the man had no recollection of being hit or being in the ambulance.
He was treated in hospital for extensive fracturing to his skull as well as bruising to his brain and bleeding on the brain. He also had extensive bruising on his face.
Wilson was arrested and cried throughout his police interview, telling officers that it was the other man who had started swearing and shouting when Wilson failed to notice him.
He said he went to push the man away and panicked when he realised what he had done, running off as he saw three other men moving to go after him.
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In a statement given within a few weeks of his release from hospital, the victim said he had never felt as scared as he did when he woke up following the assault. He described feeling miserable and staying at home all time.
The court heard his recovery had continued since then and he was soon expected to be discharged from the care of a community team.
Wilson, 25, of Briarsdale Heights, Leeds, pleaded guilty at the earliest opportunity to a single count of wounding.
A probation officer said he accepted responsibility for his actions, although it was still hard to say why he had behaved in that way.
Wilson said that at the time of the incident, he had recently left a toxic relationship, his step father was dying from a cancerous tumour, he was out of work and was using cannabis.
Now he is living in stable accommodation with family members, has a full-time job and recently became a father, the officer added.
Wilson, who was not represented, told the court that he wanted to be there for his little boy.
But the judge, Mr Recorder Ben Cox QC, said the circumstances of the assault, the severity of the physical injuries caused and the psychological impact on the victim meant there must be an immediate prison sentence.
Jailing Wilson for 18 months, he said: "What you did could have had even more serious consequences, including fatal consequences."