[When Harry blurted out the name ‘Voldmort’ which wizards are afraid of voicing, Ron gasped and said]
"You said You-Know-Who's name!" said Ron, sounding both shocked and impressed. "I'd have thought you, of all people [...]"
(Harry Potter and the Sorcerer's Stone)

What does "I'd" mean? If it is "I would," the part following "of all people" should be "you would be the last to say the name, for you lost your parents by him."; if it is "I should," the next part should be "you have the courage to say the name, then why do I have to gasp?"

[When Harry blurted out the name ‘Voldemort’ which wizards are afraid of voicing, Ron gasped and said]
"You said You-Know-Who's name!" said Ron, sounding both shocked and impressed. "I'd have thought you, of all people [...]"
(Harry Potter and the Sorcerer's Stone)

What does "I'd" mean? If it is "I would," the part following "of all people" should be "you would be the last to say the name, for you lost your parents because of him." If it is "I should," the next part should be "you have the courage to say the name, then why do I have to gasp?"

(When Harry blurted out the name ‘Voldmort’ which wizards are afraid of voicing, Ron gasped and said:)
"You said You-Know-Who's name!" said Ron, sounding both shocked and impressed. "I'd have thought you, of all people --"
(Harry Potter and the Sorcerer's Stone)

What is the original form for ‘I’d’? : when it is ‘I would,’ the last blank would be ‘of all people you would be the last to say the name, for you lost your parents by him.’ ; when it is ‘I should,’ the blank would be ‘of all people you have the courage to say the name, then why do I have to gasp?’

[When Harry blurted out the name ‘Voldmort’ which wizards are afraid of voicing, Ron gasped and said]
"You said You-Know-Who's name!" said Ron, sounding both shocked and impressed. "I'd have thought you, of all people [...]"
(Harry Potter and the Sorcerer's Stone)

What does "I'd" mean? If it is "I would," the part following "of all people" should be "you would be the last to say the name, for you lost your parents by him."; if it is "I should," the next part should be "you have the courage to say the name, then why do I have to gasp?"